1. Field of the Invention
The present invention relates to a wideband antenna module, more particularly to a wideband antenna module having a relatively small size and good isolation.
2. Description of the Related Art
Multiple-antenna systems (e.g., multiple-input and multiple-output systems, MIMO systems) are generally used to improve data rate, data throughput, spectrum efficiency, link reliability and channel capacity. However, since portable electronic devices are becoming increasingly smaller, distances among multiple antennas in the same portable electronic device are getting shorter. When two antennas are close to each other and operate at the same resonant frequency band, mutual coupling effect between the antennas will result in poor isolation therebetween, which degrades performances of the antennas.
A conventional antenna module as disclosed in U.S. Pat. No. 6,624,790 includes a protruded ground plane disposed between two antennas for improving isolation therebetween. Nevertheless, to add the protruded ground plane between two antennas may increase the size of the conventional antenna module. Moreover, a resonant frequency band at 5 GHz of the conventional antenna module is insufficient for covering WLAN 802.11a.n.